Laser cladding is a material deposition process in which a suitable material (e.g., a metal either in powder or wire form) is deposited onto a substrate by using a laser as a heat source to create a metallurgical bond between the deposited material and the substrate. Laser cladding can be used as an alternative to conventional welding and thermal spray techniques.
In some instances, laser cladding can be prone to defects, such as, excessive oxidation and porosity. The degree to which such instances occur can be dependent upon the type of material being deposited. Certain applications require extremely high quality (e.g., only limited porosity in the cladding layer being acceptable). Conventionally, a localized stream of inert shield gas is directed near the deposition site in an attempt to reduce the above-mentioned defects. However, this approach can be difficult to control.
Japanese Patent Reference JPS 54160535A is entitled, “Manufacture of Metal Mirror Blank by Laser Welding,” and it is directed to manufacturing a metal mirror blank by welding a reflecting material on a base plate under vacuum by the irradiation of a laser beam to melt the weld portion of base plate and also a laser beam to dissolve the reflecting material. After vacuumizing a vacuum container, a first laser beam from a laser generator is split by reflecting mirrors and then focused by respective condensers. The reflecting material is dispensed at the focusing point of the beam by a delivery mechanism. The reflecting material is melted and drops onto a weld portion of a base plate. A second laser beam is positioned such that its focusing point is kept apart slightly from the point on the base plate by a defocusing device such that the weld portion is slightly melted. Thus, the reflecting material is welded to the weld portion and thereby the base plate and the reflecting material forms an alloy to form the high purity material surface as the upper blank surface. The base plate is moved by the driving device and the metal mirror blank is formed on the base plate.
It will be appreciated that this background description has been created by the inventors to aid the reader, and is not to be taken as an indication that any of the indicated problems were themselves appreciated in the art. While the described principles can, in some aspects and embodiments, alleviate the problems inherent in other systems, it will be appreciated that the scope of the protected innovation is defined by the attached claims, and not by the ability of any disclosed feature to solve any specific problem noted herein.